1. Field of the Invention
This invention relates to a silicone emulsion which yields a high strength elastomer. The silicone emulsion is reinforced with a curable organic-silicone copolymer emulsion.
2. Description of the Prior Art
Cox, in U.S. Pat. No. 3,004,956, discloses a copolymer polymerized in an emulsion. His copolymer is of alkyl esters of alpha beta unsaturated monocarboxylic acids and 1 to 6 percent by weight of a compound selected from the group consisting of vinyltrimethylsilane, allyltrimethylsilane, chloroallyltrimethylsilane, vinyltriethylsilane, chloroallyltriethylsilane, and allyltriethylsilane. After removal from the emulsion, the copolymer was vulcanized by combining it with a vulcanizing agent and heating. Cox discloses no usefulness for the copolymer in the emulsion form.
In U.S. Pat. No. 3,355,406, Cekada teaches a silicone latex prepared from a colloidal suspension of a curable essentially linear siloxane polymer and a silsesquioxane in the form of a colloidal suspension. Cekada further teaches that his silicone latex could be crosslinked with silanes of the general formula A.sub.m Si(OR).sub.4-m, and catalyzed with condensation catalysts including mineral acids, strong bases, and dialkyltindiacetates. When this prepared latex was applied to a substrate and the water evaporated, a film of silicone rubber or plastic was left behind depending upon the polymer used in the latex. Cekada teaches that a silsesquioxane is an essential portion of his invention.
In U.S. Pat. No. 3,575,910, Thomas claims latex paints containing copolymers consisting essentially of 25 to 90 percent by weight of an acrylate and 10 to 75 percent by weight of a siloxane containing a vinylic radical. Thomas uses the copolymer emulsions and latex paints containing the copolymer emulsions to form coatings.
In Canadian Patent No. 842,947, Thomas includes blends of emulsion polymerized acrylate and emulsion polymerized siloxane which are pigmented and used as coatings on construction materials.
In U.S. Pat. No. 3,706,697, Backderf teaches self-curable polymers obtained by the emulsion polymerization of acryloxyalkylsilane monomers with one or more acrylic acid ester monomers. Other polymerizable comonomers up to about 64.5 percent by weight based on the total monomers may be included in the polymerization. Backderf teaches that his latex may be used per se, diluted to a lower solids content, or blended with polymer dispersions or latices of other rubbery or plastic materials. He does not teach any reason for doing so nor does he suggest any advantage in so doing.
Example 6 of U.S. Pat. No. 3,879,491 by Lindsey and Saam discloses a procedure for producing a polydiorganosiloxane modified styrene-acrylonitrile. A polydiorganosiloxane emulsion was added to a styrene and acrylonitrile mixture which was then emulsion polymerized. The styrene-acrylonitrile copolymer, after removing from the emulsion, was molded and tested to show improved impact strength.
A similar process for producing copolymers of styrenic monomers and emulsified polyorganosiloxane is taught by Hilliard in U.S. Pat. No. 3,898,300.
The cited art does not teach using the copolymers in emulsion form to reinforce a polydiorganosiloxane elastomer.